Struct DecimalSeq

pub struct DecimalSeq {
    pub num_digits: usize,
    pub decimal_point: i32,
    pub truncated: bool,
    pub digits: [u8; 768],
}

🔬This is a nightly-only experimental API. (dec2flt)

A decimal floating-point number, represented as a sequence of decimal digits.

Fields

num_digits: usize

🔬This is a nightly-only experimental API. (dec2flt)

The number of significant digits in the decimal.

decimal_point: i32

🔬This is a nightly-only experimental API. (dec2flt)

The offset of the decimal point in the significant digits.

truncated: bool

🔬This is a nightly-only experimental API. (dec2flt)

If the number of significant digits stored in the decimal is truncated.

digits: [u8; 768]

🔬This is a nightly-only experimental API. (dec2flt)

Buffer of the raw digits, in the range [0, 9].

Implementations

impl DecimalSeq

pub const MAX_DIGITS: usize = 768usize

🔬This is a nightly-only experimental API. (dec2flt)

The maximum number of digits required to unambiguously round up to a 64-bit float.

For an IEEE 754 binary64 float, this required 767 digits. So we store the max digits + 1.

We can exactly represent a float in radix b from radix 2 if b is divisible by 2. This function calculates the exact number of digits required to exactly represent that float.

According to the “Handbook of Floating Point Arithmetic”, for IEEE754, with emin being the min exponent, p2 being the precision, and b being the radix, the number of digits follows as:

−emin + p2 + ⌊(emin + 1) log(2, b) − log(1 − 2^(−p2), b)⌋

For f32, this follows as: emin = -126 p2 = 24

For f64, this follows as: emin = -1022 p2 = 53

In Python: -emin + p2 + math.floor((emin+ 1)*math.log(2, b)-math.log(1-2**(-p2), b))

pub(super) const MAX_DIGITS_WITHOUT_OVERFLOW: usize = 19usize

🔬This is a nightly-only experimental API. (dec2flt)

The max decimal digits that can be exactly represented in a 64-bit integer.

pub(super) const DECIMAL_POINT_RANGE: i32 = 2_047i32

🔬This is a nightly-only experimental API. (dec2flt)

pub(super) fn try_add_digit(&mut self, digit: u8)

🔬This is a nightly-only experimental API. (dec2flt)

Append a digit to the buffer if it fits.

pub fn trim(&mut self)

🔬This is a nightly-only experimental API. (dec2flt)

Trim trailing zeros from the buffer.

pub(super) fn round(&self) -> u64

🔬This is a nightly-only experimental API. (dec2flt)

pub(super) fn left_shift(&mut self, shift: usize)

🔬This is a nightly-only experimental API. (dec2flt)

Computes decimal * 2^shift.

pub(super) fn right_shift(&mut self, shift: usize)

🔬This is a nightly-only experimental API. (dec2flt)

Computes decimal * 2^-shift.

Trait Implementations

impl Clone for DecimalSeq

fn clone(&self) -> DecimalSeq

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DecimalSeq

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DecimalSeq

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for DecimalSeq

fn eq(&self, other: &DecimalSeq) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for DecimalSeq